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Abstract

Black grouper, Mycteroperca bonaci, are large protogynous hermaphrodites in the
Family Epinephelidae. In the Caribbean, Gulf of Mexico and South Florida they form transient
seasonal spawning aggregations in the winter and spring, with spawning timing influenced by
lunar and diel periodicities. Two small aggregations have recently been identified off the west
coast of Puerto Rico, one at Bajo de Sico, an isolated seamount, and a second off the coast of
Mona Island. Passive acoustic recorders were set at the two sites and a third at Riley’s Hump in
the Dry Tortugas. Black grouper courtship associated call (CAS) time-series were compared to
lunar and solar periodicities, water temperature and tidal stage. The populations showed similar
temporal patterns at the three spawning aggregations. Spawning season is strongly correlated
with water temperature. Within the spawning season, CAS production is significantly influenced
by lunar and solar periodicities. Production peaked between the last quarter and new moons
during evening hours. The data suggests a potential correlation with tidal stage. Temporal
patterns were consistent for three consecutive years at Mona Island. Temporal patterns were
consistent between the two larger and geographically isolated aggregations, Mona Island and
Riley’s Hump. Similar geomorphologies of these three aggregation sites indicate specific
physical characteristics can be used to help in aggregation identification. Spawning aggregations
were less than 150m from a promontory along the shelf edge at 25-35m depth and near deep
water (>100m).